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Comment by stouset | Hacker News Reader

Further, every time you trade, the overwhelming likelihood is that the counterparty to that trade is a financial professional with dramatically more access to company-specific research and information than you. This imbalance is minimized when you trade infrequently and maximized when you trade frequently.

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Meanwhile in the Theranos thread next door… “What just amazed me is how gullible all the investors were, and how they didn't do due diligence, hire outside experts, or anything. Weird.” Financial professionals do dumb things, sometimes en masse, and I think there are still some opportunities to make money if you have a good nose for BS/mass delusions.

However, the problem with this strategy is, as Keynes put it: “The market can stay irrational longer than you can stay solvent.”

It's also very easy to convince yourself that you have particular insight that those other people lack. You might even occasionally be right. But generally speaking the odds are that they understand something you don't, not the other way around.

Specifically to your Theranos point, Theranos was never public. Conning individual investors out of private investment money is somewhat different since the people who saw through the bullshit don't have an easy way of profiting off of that sense. The options were to buy in or opt out, and plenty of investors wisely decided to opt out but there was no play for them to profit off of the collapse.

For retail traders, isn't it overwhelmingly likely that you're just going to trade with the inventory of a market-neutral internalizer?

It's not either-or. You're right you're mostly trading with a market internalizer, which is pocketing the spread (ie. bid: 10.00, ask: 10.05) but isn't really making money on price movements. However, you're still against hedge funds/banks for medium/long term price movements (eg. you buying a stock after they pumped it, and selling after they dumped it).

Yeh. It would be more accurate to say something like this:

A retail trader will usually be trading with some sort of market maker. That market maker will also trade with informed traders, and sets their bid-offer spread accordingly to offset this adverse selection. So the retail trader is paying a bid-offer spread that is the result of other informed traders in the market.

Of course, as a retail investor you may have access to a broker (e.g. Robinhood) that tries to exclude informed traders so it can set a lower spread.

There are market-maker intermediaries in between but structurally you're playing the game primarily against professional finance teams with massive amounts of research, automation, and up-to-the-microsecond information you don't have access to who are the ones actually setting the price.

I don’t think that’s quite right. Otherwise, you could just follow the opposite of your unprofessional trade strategy as a cheap proxy for a professional trading strategy.

I think the market is dominated by front-running trades and randomness.

This reasoning doesn't work because the market isn't a sequence of discrete binary choices. If the "opposite" of a bad strategy was a good one anyone could have great returns by designing some obviously terrible money losing strategy then doing the "opposite".

Right, and even if the market was a sequence of discrete binary choices, bad traders will make many bad binary choices, but many of their choices will be good ones. (They just won't know which are bad and which are good.)

In other words, reversing every choice in a mediocre sequence of binary choices yields another mediocre sequence of choices.

Taking into account trading costs, a meh strategy and its inverse can both lose money.

Front-runners still have to run in front of something, though. And it's probably not going to be the purchases of some little retail investor.

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